Apparatuses and methods for compute components formed over an array of memory cells

ABSTRACT

The present disclosure includes apparatuses and methods related to compute components formed over an array of storage elements. An example apparatus comprises a base substrate material and an array of memory cells formed over the base substrate material. The array can include a plurality of access transistors comprising a first semiconductor material. A compute component can be formed over and coupled to the array. The compute component can include a plurality of compute transistors comprising a second semiconductor material. The second semiconductor material can have a higher concentration of doping ions than the first semiconductor material.

PRIORITY INFORMATION

This application claims the benefit of U.S. Provisional Application No. 62/419,004, filed Nov. 8, 2017, the contents of which are included herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory and methods, and more particularly, to apparatuses and methods related to compute components formed over an array of memory cells.

BACKGROUND

Memory devices are typically provided as internal, semiconductor, integrated circuits in computing systems. There are many different types of memory including volatile and non-volatile memory. Volatile memory can require power to maintain its data (e.g., host data, error data, etc.) and includes random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), synchronous dynamic random access memory (SDRAM), and thyristor random access memory (TRAM), among others. Non-volatile memory can provide persistent data by retaining stored data when not powered and can include NAND flash memory, NOR flash memory, and resistance variable memory such as phase change random access memory (PCRAM), resistive random access memory (RRAM), and magnetoresistive random access memory (MRAM), such as spin torque transfer random access memory (STT RAM), among others.

Computing systems often include a number of processing resources (e.g., one or more processors), which may retrieve and execute instructions and store the results of the executed instructions to a suitable location. A processing resource can comprise a number of functional units such as arithmetic logic unit (ALU) circuitry, floating point unit (FPU) circuitry, and a combinatorial logic block, for example, which can be used to execute instructions by performing logical operations such as AND, OR, NOT, NAND, NOR, and XOR, and invert (e.g., inversion) logical operations on data (e.g., one or more operands). For example, functional unit circuitry may be used to perform arithmetic operations such as addition, subtraction, multiplication, and division on operands via a number of logical operations.

A number of components in a computing system may be involved in providing instructions to the functional unit circuitry for execution. The instructions may be executed, for instance, by a processing resource such as a controller and/or host processor. Data (e.g., the operands on which the instructions will be executed) may be stored in a memory array that is accessible by the functional unit circuitry. The instructions and data may be retrieved from the memory array and sequenced and/or buffered before the functional unit circuitry begins to execute instructions on the data. Furthermore, as different types of operations may be executed in one or multiple clock cycles through the functional unit circuitry, intermediate results of the instructions and data may also be sequenced and/or buffered.

In many instances, the processing resources (e.g., processor and/or associated functional unit circuitry) may be external to the memory array, and data is accessed via a bus between the processing resources and the memory array to execute a set of instructions. Processing performance may be improved in an in-memory intelligence (IMI) device, which can also be referred to as a processing-in-memory (PIM) device, in which a processing resource may be implemented internal and/or near to a memory (e.g., directly on a same chip as the memory array). An IMI device may reduce time in processing and may also conserve power. Data movement between and within arrays and/or subarrays of various memory devices, such as IMI devices, can affect processing time and/or power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an apparatus in the form of a computing system including a memory device in accordance with a number of embodiments of the present disclosure.

FIG. 2 is a block diagram illustrating a cross-sectional view of a portion of a memory device in accordance with a number of embodiments of the present disclosure.

FIG. 3 is a schematic diagram illustrating a cross-sectional view of a portion of a memory device in accordance with a number of embodiments of the present disclosure.

FIG. 4 is a schematic diagram illustrating a cross-sectional view of a portion of a memory device comprising layered memory tiers in accordance with a number of embodiments of the present disclosure.

FIG. 5 is a schematic diagram illustrating sensing circuitry in accordance with a number of embodiments of the present disclosure.

FIG. 6 is a logic table illustrating selectable logic operation results implemented by sensing circuitry in accordance with a number of embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes apparatuses and methods related to compute components formed over an array of memory cells. An example apparatus comprises a base substrate material and an array of memory cells formed over the base substrate material. The array can include a plurality of access transistors comprising a first semiconductor material. The compute component can be formed over and coupled to the array. The compute component can include a plurality of compute transistors comprising a second semiconductor material. Sensing circuitry can be formed over and coupled to the array, wherein the sensing circuitry comprises the compute component and a sense amplifier coupled to the compute component. The second semiconductor material can have a higher concentration of doping ions than the first semiconductor material. The second semiconductor material having a higher concentration of doping ions than the first semiconductor material can be done as part of optimizing leakage characteristics of transistors, such as access transistors, for a low leakage current.

In some approaches, memory devices may comprise an array of memory cells formed on a base substrate material. A memory device may be formed from the bottom up, starting with the base substrate material. Access transistors and sensing circuitry may be formed in the base substrate material. However, forming the array of memory cells may require several heating cycles. These heating cycles affect the concentration of doping ions in semiconductor components formed prior to the heating cycles by lowering the concentration of doping ions.

Doping ions in a semiconductor material formed prior to the heating cycles needed to form a storage element (e.g., a memory cell) can move during the heating cycles such that the ions disperse in the substrate, forming leakage paths. Thus, a semiconductor component that was heavily doped so as to have a high concentration of doping ions may end up having significant leakage paths as a result of the subsequent heating cycles. While, a lower concentration of doping ions may result in slower transistors as a function of increased resistance, it also may result in lower leakage currents. Lower leakage currents for access transistors (e.g., DRAM access transistors) may enhance DRAM data retention time. These lower leakage currents can help preserve charge stored in a storage element coupled to an access transistor from leaking array from the storage element. If charge leaks out then a data value stored in the storage element can changed over time. Consequently, it can be beneficial to have the base substrate material and the access transistors of a memory device to have a low concentration of doping ions. Therefore, access transistors that are formed in the base substrate material can be formed having an initial low concentration of doping ions.

An IMI device can comprise a compute component, which can comprise a plurality of compute transistors used in performing computations on data stored in the array. The compute component can benefit from being formed of a semiconductor material having a higher concentration of doping ions. Doping a semiconductor material to a high concentration of doping ions causes the semiconductor material to become a better conductor of electricity. As a better conductor of electricity, transistors formed in the material having a high concentration of doping ions can switch faster and have shorter switching times than the other semiconductor components, such as access transistors formed in a semiconductor material having a low concentration of doping ions.

Because the compute component can comprise transistors (e.g., a plurality of compute transistors) used to perform computations, via performing logic operations, it can be beneficial to form transistors of the compute component having a high concentration of doping ions. A semiconductor material having a high concentration of doping ions can have a high leakage current. If components other than the compute component, such as access transistors, have a high leakage current, then the memory cell retention time for those components can be shortened. As used herein, “memory cell retention time” refers to the time which a memory cell is able to hold a charge, which can correspond to data, such that when the memory cell is read (e.g., by a sense amplifier) the data is interpreted correctly. Because transistors of the compute component are not used for data storage, a higher leakage current is not problematic, but rather beneficial because of the shorter switching times. In an IMI device that includes an array of storage elements where the storage elements formed over each other (e.g., layered), the heating cycles can compound the dispersal of doping ions of semiconductor components formed before the storage elements, further exasperating the tradeoffs between fast switching transistors for logic transistors and low-leaking transistors for storage (e.g., DRAM storage).

At least one embodiment of the present disclosure can include a memory device being a multi-layer memory device. In a multi-layer memory device where multiple semiconductor materials are formed on top of each other (e.g., a layered formation), semiconductor materials formed before (e.g., lower layers) other semiconductor materials (e.g., upper layers) can be subjected to more heating cycles than the other semiconductor materials (e.g., the upper layers). A lowered concentration of doping may negatively affect the performance of the compute transistors, and consequently the performance of the IMI device. Thus, it can be beneficial to form semiconductor materials having a high concentration of doping ions after forming the lower layers (e.g., as an uppermost layer(s)) such that the high concentration of doping ions in the uppermost layer(s) can be maintained. Thus, it can be beneficial to form the compute component after an array of storage elements has been formed.

By forming compute circuitry in a semiconductor material formed over an array of storage elements, the compute component in the semiconductor material is not subjected to the heating cycles from forming the array of storage elements. Thus, a greater level of control of the concentration of doping ions in the semiconductor material can be achieved such that the concentration of doping ions of the semiconductor material can be maintained.

In the following detailed description of the present disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how one or more embodiments of the disclosure may be practiced. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice the embodiments of this disclosure, and it is to be understood that other embodiments may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure. As used herein, designators such as “n”, particularly with respect to reference numerals in the drawings, indicate that a number of the particular feature so designated can be included. As used herein, “a number of” a particular thing refers to one or more of such things (e.g., a number of memory arrays can refer to one or more memory arrays). A “plurality of” is intended to refer to more than one of such things.

The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 215 may reference element “15” in FIG. 2, and a similar element may be referenced as 315 in FIG. 3. As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, and/or eliminated so as to provide a number of additional embodiments of the present disclosure. In addition, as will be appreciated, the proportion and the relative scale of the elements provided in the figures are intended to illustrate certain embodiments of the present invention, and should not be taken in a limiting sense.

FIG. 1 is a block diagram of an apparatus in the form of a computing system 100 including a memory device 102 in accordance with a number of embodiments of the present disclosure. As used herein, a memory device 102, a controller 103, a memory array 110, and/or sensing circuitry 106 might also be separately considered an “apparatus.”

The system 100 includes a host 101 coupled (e.g., connected) to the memory device 102, which includes a memory array 110. The host 101 can be a host system such as a personal laptop computer, a desktop computer, a digital camera, a smart phone, or a memory card reader, among various other types of hosts. The host 101 can include a system motherboard and/or backplane and can include a number of processing resources (e.g., one or more processors, microprocessors, or some other type of controlling circuitry). The system 100 can include separate integrated circuits or both the host 101 and the memory device 102 can be on the same integrated circuit. The system 100 can be, for instance, a server system and/or a high performance computing (HPC) system and/or a portion thereof. Although the example shown in FIG. 1 illustrates a system having a Von Neumann architecture, embodiments of the present disclosure can be implemented in non-Von Neumann architectures, which may not include one or more components (e.g., CPU, ALU, etc.) often associated with a Von Neumann architecture.

For clarity, the system 100 has been simplified to focus on features with particular relevance to the present disclosure. The memory array 110 can be a hybrid memory cube (HMC), computational memory such as a processing-in-memory random access memory (PIMRAM) array, which can include one or more of a DRAM array, SRAM array, STT RAM array, PCRAM array, TRAM array, RRAM array, NAND flash array, and/or NOR flash array, for instance. The memory array 110 can comprise memory cells arranged in rows coupled by access lines, which may be referred to herein as word lines or select lines, and columns coupled by digit lines, which may be referred to herein as bit lines, data lines, or sense lines. Although a single memory array 110 is shown in FIG. 1, embodiments are not so limited. For instance, the memory device 102 may include a number of memory arrays 110 (e.g., a number of banks of DRAM cells, NAND flash cells, etc.).

The memory device 102 can include address circuitry 104 to latch address signals for data provided over an input/output “I/O” bus 172 (e.g., data bus and/or address bus) through I/O circuitry 109 (e.g., provided to external ALU circuitry and to DRAM DQs via local I/O lines and global I/O lines). Address signals are received through address circuitry 104 and decoded by a row decoder 105 and a column decoder 107 to access the memory array 110. Data can be read from the memory array 110 by sensing voltage and/or current changes on the digit lines using the sensing circuitry 106. The sensing circuitry 106 can read and latch a page (e.g., row) of data from the memory array 110. The I/O circuitry 109 can be used for bi-directional data communication with the host 101 over the I/O bus 172. In a number of embodiments, sensing circuitry 106 can include a number of sense amplifiers and a respective number of compute components as will be discussed further herein. The write circuitry 108 can be used to write data to the memory array 110.

The controller 103 (e.g., memory controller) decodes signals provided by the control bus 170 from the host 101. These signals can include chip enable signals, write enable signals, and address latch signals that are used to control operations performed on the memory array 110, including data read, data write, and data erase operations. In various embodiments, the controller 103 is responsible for executing instructions from the host 101 and sequencing access to the memory array 110. The controller 103 can be a state machine, sequencer, or some other type of controller, and include hardware and/or firmware (e.g., microcode instructions) in the form of an application specific integrated circuit (ASIC). The controller 103 can control, for example, generation of clock signals and application of the clock signals to a compute component in sensing circuitry in association with shifting data in accordance with embodiments described herein.

In a number of embodiments, the sensing circuitry 106 can comprise a sense amplifier and a compute component. The compute component may also be referred to herein as an accumulator, and can be used to perform logical operations (e.g., on data associated with a pair of complementary digit lines). The compute component can comprise a plurality of transistors, which can be referred to as compute transistors. According to various embodiments, the compute component comprises a first storage location and a second storage location. The first and second storage locations of the sensing components can serve as stages of a shift register. For example, clock signals can be applied to the sensing components to move data values between the first and second storage locations and to shift data between adjacent sensing components.

In a number of embodiments, the sensing circuitry 106 can be used to perform logical operations using data stored in the memory array 110 as inputs and/or store the results of the logical operations back to the memory array 110 without transferring data via a digit line address access (e.g., without firing a column decode signal). As such, various compute functions can be performed using, and within, the sensing circuitry 106 rather than (or in association with) being performed by processing resources external to the sensing circuitry 106 (e.g., by a processing resource associated with the host 101 and/or other processing circuitry, such as ALU circuitry, located on device 102 (e.g., on the controller 103 or elsewhere)).

In various previous approaches, data associated with an operand, for instance, would be read from memory via sensing circuitry and provided to external ALU circuitry via I/O lines (e.g., via local I/O lines and/or global I/O lines). The external ALU circuitry could include a number of registers and would perform compute functions using the operands, and the result would be transferred back to the array via the I/O lines. In contrast, in a number of embodiments of the present disclosure, the sensing circuitry 106 is configured to perform logical operations on data stored in the memory array 110 and store the result back to the memory array 110 without enabling an I/O line (e.g., a local I/O line) coupled to the sensing circuitry 106.

As such, in a number of embodiments, circuitry external to the memory array 110 and sensing circuitry 106 is not needed to perform compute functions as the sensing circuitry 106 can perform the appropriate logical operations to perform such compute functions without the use of an external processing resource. Therefore, the sensing circuitry 106 may be used to complement and/or to replace, at least to some extent, such an external processing resource (or at least the bandwidth consumption of such an external processing resource).

However, in a number of embodiments, the sensing circuitry 106 may be used to perform logical operations (e.g., to execute instructions) in addition to logical operations performed by an external processing resource (e.g., the host 101). For instance, the host 101 and/or sensing circuitry 106 may be limited to performing only certain logical operations and/or a certain number of logical operations.

In a number of embodiments, the sensing circuitry 106 can be formed on a same pitch as a pair of complementary sense lines of the array. For example, the cells of a memory array may have a 4F² or 6F² cell size, where “F” is a feature size corresponding to the cells. As an example, a pair of complementary memory cells may have a cell size with a 6F² pitch (e.g., 3F×2F). If the pitch of a pair of complementary sense lines for the complementary memory cells is 3F, then the sensing circuitry being on pitch indicates the sensing circuitry (e.g., a sense amplifier and corresponding compute component per respective pair of complementary sense lines) is formed to fit within the 3F pitch of the complementary sense lines.

Enabling an I/O line can include enabling (e.g., turning on) a transistor having a gate coupled to a decode signal (e.g., a column decode signal) and a source/drain coupled to the I/O line. However, embodiments are not limited to performing logical operations using sensing circuitry (e.g., the sensing circuitry 106) without enabling column decode lines of the memory array 110. Whether or not local I/O lines are used in association with performing logical operations via sensing circuitry 106, the local I/O line(s) may be enabled in order to transfer a result to a suitable location other than back to the memory array 110 (e.g., to an external register).

FIG. 2 is a block diagram illustrating a cross-sectional view of a portion of a memory device 202 in accordance with a number of embodiments of the present disclosure. For illustration purposes only, a set of axes 211 are used to show the orientation of a cross-sectional view of the portion of a multi-layer memory device 202. The x-direction follows the width of the page and the z-direction follows the length of the page. The y-direction (not shown) is into and out of the page. The memory device 202 can be analogous to the memory device 102 illustrated in FIG. 1. In the embodiment of FIG. 2, the memory device 202 is a multi-layer memory device. The memory device 202 can comprise a base substrate material 215, a first semiconductor material 262 formed over the base substrate material 215, and a second semiconductor material 264 formed over the first semiconductor material 262. The base substrate material 215 can be a monocrystalline silicon base substrate. The first semiconductor material 262 can be an amorphous silicon first semiconductor material. The second semiconductor material 264 can be an amorphous silicon second semiconductor material. Although FIG. 2 shows two semiconductor materials, the first semiconductor material 262 and the second semiconductor material 264, any number of semiconductor materials can be formed over the base substrate material 215. For example, a third semiconductor material (not shown) can be formed over the second semiconductor material 264, a fourth semiconductor material (not shown) can be formed over the third semiconductor material, and so on.

A plurality of access transistors can be formed in the base substrate material 215 or formed over the base substrate material 215 such that the plurality of access transistors comprises the first semiconductor material 262. The plurality of access transistors can be coupled to an array of storage elements formed over the base substrate material 215. In at least one embodiment in accordance with the present disclosure, the array of storage elements can include the plurality of access transistors directly coupled to the storage elements such that the storage elements and the plurality of access transistors together comprise an array of memory cells (e.g., a DRAM array). Examples of arrays of memory cells in accordance with the present disclosure are illustrated in FIGS. 3 and 4.

A compute component (not shown), which can comprise a plurality of compute transistors, can be formed over the array of storage elements such that the plurality of compute transistors comprises the second semiconductor material 264. The memory device 202 can comprise a plurality of metal interconnects (not shown) that interconnects, the plurality of access transistors, the array of storage elements, and the compute component.

In at least one embodiment in accordance with the present disclosure, a first portion of the sensing circuitry (e.g., a sense amplifier) can be formed in the base substrate material 215 and a second portion of the sensing circuitry (e.g., at least a portion of the compute component) can be formed over the array of storage elements. For example, a plurality of sense amplifiers can be formed in the base substrate material 215 as part of the first portion of the sensing circuitry and a plurality of compute transistors of the compute component comprising the second semiconductor material 264 can be formed over the array of storage elements as part of the second portion of the sensing circuitry.

The second semiconductor material 264 can be doped to a higher doping concentration than the first semiconductor material 262 or the base substrate material 215. A higher concentration of doping ions can decrease the leakage current. As discussed above, high leakage currents can hinder the performance of a memory array because memory cell retention times can be diminished. However, a lower concentration of doping ions can correspond to shorter refresh intervals. For example, compute transistors formed of the second semiconductor material 264 having a low concentration of doping ions can have shorter refresh intervals than access transistors formed of the first semiconductor material 262 or the base substrate material 215 having a high concentration of doping ions. Faster switching can be a function of a shorter refresh cycle time. Access transistors having short refresh intervals can be detrimental to the performance of a memory array.

FIG. 3 is a schematic diagram illustrating a cross-sectional view of a portion of a memory device 302 in accordance with a number of embodiments of the present disclosure. For illustration purposes only, a set of axes 311 are used to show the orientation of a cross-sectional view of the memory array 310. The x-direction follows the width of the page and the z-direction follows the length of the page. The y-direction (not shown) is into and out of the page. The memory device 302 can be analogous to the memory device 102 illustrated in FIG. 1. The memory array 310 can be analogous to the memory array 110 illustrated in FIG. 1. The base substrate material 315 can be analogous to the base substrate material 215 illustrated in FIG. 2.

FIG. 3 illustrates a portion of an array of memory cells comprising two transistor-one capacitor (2T-1C) memory cells. Specifically, a pair of adjacent memory cells 312 and 312 a are illustrated. A box 313 demarcates an approximate boundary of the memory cell 312. The memory cells 312 and 312 a can be substantially identical to one another, with the term “substantially identical” meaning that the memory cells are identical to within reasonable tolerances of fabrication and measurement.

The illustrated portion of the array of memory cells is supported by a base substrate material 315. The base substrate material 315 can comprise a semiconductor material; and can, for example, comprise, consist essentially of, or consist of monocrystalline silicon. The base substrate material 315 may be referred to as a semiconductor substrate. The term “semiconductor substrate” means any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductor substrates described above. In some embodiments, the base substrate material 315 can correspond to a semiconductor substrate containing one or more materials associated with integrated circuit fabrication. Such materials can include, for example, one or more of refractory metal materials, barrier materials, diffusion materials, insulator materials, etc.

The base substrate material 315 is shown to be spaced from components of the memory array 310 to indicate that other circuitry or components may be between the memory cells 312 and 312 a and the base substrate material 315. For example, additional pairs of memory cells 312 and 312 a can be formed between the memory cells 312 and 312 a illustrated in FIG. 3 and the base substrate material 315. Although FIG. 3 illustrates sensing circuitry 306, which can be analogous to the sensing circuitry 106 illustrated in FIG. 1, being located above the memory array 310, a portion of the sensing circuitry 306 can be formed between the memory cells 312 and 312 a and the base substrate material 315. For example, sense amplifiers 380 and 380 a of the sensing circuitry 306 can be formed in the base substrate material 315 such that the compute components 382 and 382 a without sense amplifiers 380 and 380 a are located above the memory array 310. Although FIG. 3 illustrates the compute components 382 and 382 a being located above the memory array 310, a portion of the compute components 382 and 382 a (e.g., the latch 591 illustrated in FIG. 5) can be formed between the memory cells 312 and 312 a and the base substrate material 315. An interlayer insulating film 317 can intervene between the base substrate material 315 and the memory array 310. The insulating film 317 can comprise any suitable electrically insulative material or combination of insulative materials, including, for example, silicon dioxide, silicon nitride, etc.

In the illustrated embodiment, the insulating film 317 has a substantially planar upper surface, and the comparative digit lines (e.g., bit lines (BL)) BL-1, BL-2, BL-1 a and BL-2 a are disposed on such upper surface, and in parallel with one another. The term “substantially planar” means planar to within reasonable tolerances of fabrication and measurement.

The memory cell 312 comprises a pair of complementary digit lines BL-1 and BL-2, and comprises transistors T1 and T2 over the digit lines BL-1 and BL-2, respectively. Similarly the memory cell 312 a comprises a pair of complementary digit lines BL-1 a and BL-2 a, and comprises transistors T1 a and T2 a. The pair of complementary digit lines BL-1 and BL-2 can be coupled to sensing circuitry 306. The sensing circuitry 306 can be formed over the memory cells 312 and 312 a. Similarly, the pair of complementary digit lines BL-1 a and BL-2 a can be coupled to the sensing circuitry 306.

As illustrated in FIG. 3, the complementary pair of digit lines BL-1 and BL-2 of memory cell 312 are laterally displaced relative to one another, and similarly the transistors T1 and T2 are laterally displaced relative to one another. The transistors T1 and T2 are shown to be in a common horizontal plane as one another (i.e., are horizontally aligned with one another), but in other embodiments can be vertically offset relative to one another.

The transistors T1 and T2 comprise gates 314 and 316; and similarly the transistors T1 a and T2 a comprise gates 314 a and 316 a. The memory cells 312 and 312 a are in a common row as one another within the memory array, and accordingly a word line (WL) extends across all of the transistors T1, T1 a, T2 and T2 a, and comprises the gates of the transistors. The word line and the digit lines can comprise any suitable electrically conductive material, including, for example, one or more of various metals (e.g., tungsten, titanium, etc.), metal containing compositions (e.g., metal nitride, metal carbide, metal silicide, etc.), conductively-doped semiconductor materials (e.g., conductively-doped silicon, conductively-doped germanium, etc.), etc. The word line and digit lines may comprise the same composition as one another, or can comprise different compositions relative to one another.

Semiconductor pillars 318 and 320 extend upwardly from the complementary digit lines BL-1 and BL-2. Similarly, semiconductor pillars 318 a and 320 a extend upwardly from the complementary digit lines BL-1 a and BL-2 a. Semiconductor pillars 318, 320, 318 a, and 320 a can comprise any suitable semiconductor materials including, for example, one or both of silicon and germanium.

The semiconductor pillars 318, 320, 318 a and 320 a can comprise a first semiconductor material. The first semiconductor material can be analogous to the first semiconductor material 262 illustrated in FIG. 2. The first semiconductor material can be doped to a first concentration of doping ions. The first concentration can be such that the transistors T1, T2, T1 a, and T2 a have a low leakage current. A low leakage current can improve data retention because charge stored on the capacitors 338 and 338 a may not leak out of the capacitors 338 and 338 a through the corresponding transistors T1, T2, T1 a, and T2 a. The second semiconductor material, in which the compute components 382 and 382 a or the sensing circuitry 306 can be formed, can be doped to a second concentration of doping ions. The second concentration can be higher, or lower, than the first concentration.

The transistor gate 314 is spaced from the semiconductor pillar 318 by a gate dielectric material 322, and the transistor gate 316 is spaced from the semiconductor pillar 320 by a gate dielectric material 324. The gate dielectric materials 322 and 324 can comprise any suitable compositions or combinations of compositions, including, for example, silicon dioxide, silicon nitride, high-K dielectric material, ferroelectric material, etc. The gate dielectric materials 322 a and 324 a within the transistors T1 a and T2 a can be analogous to the gate dielectric materials 322 and 324.

The transistor T1 comprises a channel region 326 within the semiconductor pillar 318, and comprises source/drain regions 328 and 330 on opposing sides of the channel region. The source/drain regions 328 and 330 and the channel region 326 can be doped with any suitable doping ions. In some embodiments, the source/drain regions 328 and 330 can be n-type majority doped, and in other embodiments may be p-type majority doped.

The transistor T2 comprises a channel region 332 within the semiconductor pillar 320, and comprises source/drain regions 334 and 336 on opposing sides of the channel region 332. In some embodiments, the source/drain regions 334 and 336 may be n-type majority doped, and in other embodiments can be p-type majority doped. In some embodiments, the source/drain regions 328 and 330 can be referred to as first and second source/drain regions, respectively; and the source/drain regions 334 and 336 can be referred to as third and fourth source/drain regions, respectively.

The transistors T1 a and T2 a comprise source/drain regions 328 a, 330 a, 334 a, and 336 a and channel regions 326 a and 332 a, which can be analogous those described with reference to the transistors T1 and T2.

As shown in FIG. 3, sensing circuitry 306 can comprise a sense amplifier 380 coupled to the pair of complementary digit lines BL-1 and BL-2 via metal interconnects 368 and a sense amplifier 380 a coupled to the pair of complementary digit lines BL-1 a and BL-2 a via metal interconnects 368 a. The sense amplifiers 380 and 380 a can be coupled to compute components 382 and 382 a, respectively. The compute components 382 and 382 a can be a discrete collection of elements. For example, the compute components 382 and 382 a can comprise a plurality of compute transistors (which can be referred to as “Boolean logic”), an accumulator storage location, and a shift storage location. The plurality of compute transistors can comprise a second semiconductor material. The second semiconductor material can be analogous to the second semiconductor material 264 illustrated in FIG. 2. The second semiconductor material can be doped to a second concentration of doping ions. Although not illustrated in FIG. 3, the compute components 382 and 382 a can include selectable logical operation selection logic.

In some embodiments, the compute components 382 and 382 a can be coupled to another compute component such that data values (e.g., bits) can be moved (e.g., shifted) from one compute component to another compute component. Shifting data values between one compute component and another compute component may be done synchronously such that a compute component receives a data value from another compute component as the compute component passes its data value to yet another compute component. In some embodiments, shifting data in the compute components 382 and 382 a can facilitate various processing functions such as the multiplication, addition, etc. of two operands.

The memory cell 312 comprises a capacitor 338 which is vertically displaced relative to transistors T1 and T2, and as illustrated in FIG. 3, is over the transistors T1 and T2. The capacitor 338 can be a storage element. The capacitor 338 comprises an outer node (or first node) 340, an inner node (or second node) 342, and a capacitor dielectric material 344 between the outer and inner nodes 340 and 342. In the embodiment of FIG. 3 the outer node 340 is container-shaped, and the inner node 342 and the capacitor dielectric material 344 extend into the container-shaped outer node 340. In some embodiments, the outer node 340 can have a different configuration (e.g., a planar configuration).

The outer and inner nodes 340 and 342 can comprise any suitable electrically conductive compositions or combinations of electrically conductive compositions, including, for example, one or more of various metals (e.g., tungsten, titanium, etc.), metal containing materials (for instance, metal nitride, metal silicide, metal carbide, etc.), conductively-doped semiconductor materials (for instance, conductively-doped silicon, conductively-doped germanium, etc.), etc. The outer and inner nodes 340 and 342 can comprise the same composition as one another in some embodiments, and in other embodiments can comprise different compositions relative to one another.

The capacitor dielectric material 344 can comprise any suitable composition or combination of compositions. In some embodiments, the capacitor dielectric material may comprise non-ferroelectric material and may, for example, consist of one or more of silicon dioxide, silicon nitride, aluminum oxide, hafnium oxide, zirconium oxide, etc. In some embodiments the capacitor dielectric material may comprise ferroelectric material. For instance, the capacitor dielectric material may comprise, consist essentially of, or consist of one or more materials selected from the group consisting of transition metal oxide, zirconium, zirconium oxide, hafnium, hafnium oxide, lead zirconium titanate, tantalum oxide, and barium strontium titanate; and having dopant therein which comprises one or more of silicon, aluminum, lanthanum, yttrium, erbium, calcium, magnesium, niobium, strontium, and a rare earth element.

As illustrated in FIG. 3, the outer electrode 340 is electrically coupled with the first source/drain region 328 of transistor T1, and the inner electrode 342 is electrically coupled with the third source/drain region 334 of transistor T2. The second source/drain region 330 of transistor T1 is electrically coupled with complementary digit line BL-1 and the fourth source/drain region 336 of transistor T2 is electrically coupled with complementary digit line BL-2. The capacitor 338, together with transistors T1 and T2, and complementary digit lines BL-1 and BL-2, forms a 2T-1C memory cell. The inner electrode 342 is shown having a single homogenous composition that extends from inside of the container-shaped outer electrode 340 to outside of the container-shaped outer electrode 340 and into electrical contact with the source/drain region 334. In some embodiments, at least some of the illustrated portion of the inner electrode 342 outside of the container-shaped outer electrode 340 can be replaced with an electrically conductive interconnect which may or may not have a same composition as the inner electrode 342.

The memory cell 312 a comprises a capacitor 338 a, which can be analogous to the capacitor 338 of the memory cell 312 (with the capacitor 338 a comprising a first node 340 a, a second node 342 a, and a capacitor dielectric material 344 a), and also comprises a 2T-1C memory cell.

An insulative material 348 is shown to surround the various components of memory cells 312 and 312 a. Such insulative material may comprise any suitable composition or combination of compositions; including, for example, one or more of silicon dioxide, silicon nitride, borophosphosilicate glass, spin-on dielectric, etc. Although the insulative material 348 is shown as a single homogeneous material, in other embodiments the insulative material may include two or more discrete insulative compositions.

Although not illustrated in FIG. 3, the embodiment illustrated in FIG. 3 can include global metal interconnects and pads directly coupled to the sensing circuitry 306. A benefit of having the global metal interconnects and pads directly coupled to the sensing circuitry 306 can be reduced resistive and capacitive loads on the interface between the memory array 310 and other devices or components coupled to the memory array 310 (e.g., transmitting data to and from the memory array 310). The reduction of the resistive and capacitive loads can be a result of the shorter distance between the sensing circuitry and the global metal interconnects and pads.

A controller, such as the controller 103 illustrated in FIG. 1, can be coupled to the memory array 310 and the sensing circuitry 306, for example, via the global metal interconnects and pads (not shown). Although not illustrated in FIG. 3, in an embodiment where sense amplifiers 380 and 380 a are located elsewhere in the memory device 302, such as being formed in the base substrate material 315, the controller can be, for example, coupled to the memory array 310 and the compute components 382 and 382 a via the global metal interconnects and pads (not shown) and to the sense amplifiers 380 and 380 a via the metal interconnects 368 and 368 a. The controller can be configured to cause data to be transmitted, via the metal interconnects 368 and 368 a, between the memory cells 312 and 312 a, the sensing circuitry 306, and the global metal interconnects and pads.

The controller can be directly coupled to the global metal interconnects and pads (not shown) such that the controller is formed over the uppermost semiconductor material of a multi-layer memory device. Minimizing the distance between the controller and the compute transistors can enhance the benefit of compute components comprising a semiconductor material having a lower concentration of doping ions formed over a semiconductor material having a lower concentration of doping ions.

FIG. 4 is a schematic diagram illustrating a cross-sectional view of a portion of a memory device comprising layered memory tiers 452 and 454 in accordance with a number of embodiments of the present disclosure. The memory device 402 can be analogous to the memory device 102 illustrated in FIG. 1. The memory array 410 can be analogous to the memory array 110 illustrated in FIG. 1. The base substrate material 415 can be analogous to the base substrate material 215 illustrated in FIG. 2. The sensing circuitry 406 can be analogous to the sensing circuitry 306 illustrated in FIG. 3. The sense amplifiers 480 and 480 a, the compute components 482 and 482 a, and the metal interconnects 468 and 468 a can be analogous to the sense amplifiers 380 and 380 a, the compute components 382 and 382 a, and the metal interconnects 368 and 368 a illustrated in FIG. 3, respectively.

FIG. 4 illustrates an array of memory cells in the form of layered memory array tiers. For illustration purposes only, a set of axes 411 are used to show the orientation of a cross-sectional view of the memory device 402. The x-direction follows the width of the page and the z-direction follows the length of the page. The y-direction (not shown) is into and out of the page. A second memory array tier 454 is formed on a first memory array tier 452. The first memory array tier 452 comprises memory cells 412 and 412 a, which can be analogous the memory cells 312 and 312 a illustrated in FIG. 3. The second memory array tier 454 comprises memory cells 412 b and 412 c that are analogous to the memory cells 412 and 412 a, except that the memory cells 412 b and 412 c are inverted relative to the memory cells 412 and 412 a. The memory cell 412 b comprises first and second transistors T1 b and T2 b, and the memory cell 412 c comprises first and second transistors T1 c and T2 c. The memory cells 412 b and 412 c comprise capacitors 438 b and 438 c, respectively. The word line extending across the memory cells 412 and 412 a is labeled as a first word line WL1, and the word line across the memory cells 412 b and 412 c is labeled as a second word line WL2.

The complementary digit lines BL-1 and BL-2 can be coupled to sensing circuitry 406 formed over the memory cells 412 b and 412 c. Although FIG. 4 illustrates sensing circuitry 406 being located above the memory array 410, a portion of the sensing circuitry 406 can be formed between the memory cells 412 and 412 a and the base substrate material 415. For example, sense amplifiers 480 and 480 a of the sensing circuitry 406 can be formed in the base substrate material 415 such that the compute components 482 and 482 a without sense amplifiers 480 and 480 a are located above the memory array 410. Although FIG. 4 illustrates the compute components 482 and 482 a being located above the memory array 410, a portion of the compute components 482 and 482 a (e.g., the latch 591 illustrated in FIG. 5) can be formed between the memory cells 412, 412 a, 412 b, and 412 c, and the base substrate material 415. The complementary digit lines BL-1 a and BL-2 a can be coupled to the sensing circuitry 406. As shown in FIG. 4, sensing circuitry can comprise the sense amplifier 480 coupled to the complementary digit lines BL-1 and BL-2 via metal interconnects 468 and the sense amplifier 480 a coupled to the complementary digit lines BL-1 a and BL-2 a via metal interconnects 468 a. The sense amplifiers 480 and 480 a can be coupled to compute components 482 and 482 a, respectively. The compute components 482 and 482 a can be a discrete collection of elements. For example, the compute components 482 and 482 a can comprise a plurality of compute transistors (which can be referred to as “Boolean logic”), an accumulator storage location, and a shift storage location. The plurality of compute transistors can comprise a second semiconductor material. The second semiconductor material can be analogous to the second semiconductor material 264 illustrated in FIG. 2. The second semiconductor material can be doped to a second concentration of doping ions. As discussed above, because the plurality of compute transistors of the sensing components are formed on and after the memory cells 412, 412 a, 412 b, and 412 c, the plurality of compute transistors can be formed with a high doping concentration corresponding to faster operation without the concern that subsequent heating cycles will cause the doping concentration to decrease.

The transistors T1, T2, T1 a, T2 a, T1 b, T2 b, T1 c, and T2 c can comprise a first semiconductor material. The first semiconductor material can be analogous to the first semiconductor material 262 illustrated in FIG. 2. The first semiconductor material can be doped to a first doping concentration. The first doping concentration can be such that the transistors T1, T2, T1 a, T2 a, T1 b, T2 b, T1 c, and T2 c have a low leakage current. A low leakage current can improve data retention because charge stored on the capacitors 438, 438 a, 438 b, and 438 c will not leak out through the capacitors 438 and 438 a corresponding the transistors T1, T2, T1 a, T2 a, T1 b, T2 b, T1 c, and T2 c.

The base substrate material 415 is shown to be spaced from components of the memory device 402 to indicate that other circuitry or components may be between the memory cells 412, 412 a, 412 b, and 412 c and the base substrate material 415. For example, additional sets of memory cells 412, 412 a, 412 b, and 412 c can be formed between the memory cells 412, 412 a, 412 b, and 412 c illustrated in FIG. 4 and the base substrate material 415.

In some embodiments, an axis 453 through the complementary digit lines BL-1, BL-2, BL-1 a, and BL-2 a can be considered to define a mirror plane and the memory cells 412 b and 412 c may be considered to be substantially mirror images of the memory cells 412 and 412 a, respectively, across the mirror plane. The term “substantially mirror images” is utilized to indicate that the indicated cells may be mirror images of one another to within reasonable tolerances of fabrication and measurement.

In some embodiments, the configuration of FIG. 3 can be considered to comprise memory cells within 4F² architecture, and the configuration of FIG. 4 can be considered to comprise memory cells within 8F² architecture.

Although not illustrated in FIG. 4, the embodiment illustrated in FIG. 4 can include global metal interconnects and pads directly coupled to the sensing circuitry 406. A benefit of having the global metal interconnects and pads directly coupled to the sensing circuitry 406 can be reduced resistive and capacitive loads on the interface between the memory array 410 and other components of the memory device 402 (e.g., transmitting data to and from the memory array 410). The reduction of the resistive and capacitive loads can be a result of the shorter distance between the sensing circuitry 406 and the global metal interconnects and pads. Although not illustrated in FIG. 4, the compute components 482 and 482 a can include selectable logical operation selection logic

A controller, such as the controller 103 illustrated in FIG. 1, can be coupled to the memory array 410 and the sensing circuitry 406, for example, via the global metal interconnects and pads (not shown). Although not illustrated in FIG. 4, in an embodiment where sense amplifiers 480 and 480 a are located elsewhere in the memory device 402, such as being formed in the base substrate material 415, the controller can be, for example, coupled to the memory array 410 and the compute components 482 and 482 a via the global metal interconnects and pads (not shown) and to the sense amplifiers 480 and 480 a via the metal interconnects 468 and 468 a. The controller can be configured to cause data to be transmitted, via the metal interconnects 468 and 468 a, between the memory cells 412, 412 a, 412 b, and 412 c, the sensing circuitry 406, and the global metal interconnects and pads.

The controller can be directly coupled to the global metal interconnects and pads (not shown) such that the controller is formed over the uppermost semiconductor material of a multi-layer memory device. Minimizing the distance between the controller and the compute transistors can enhance the benefit of compute components comprising a semiconductor material having a lower concentration of doping ions formed over a semiconductor material having a lower concentration of doping ions.

At least one embodiment in accordance with the present disclosure can include forming an array of storage elements over a base substrate material. A semiconductor material can be formed over the array of storage elements. Forming the semiconductor material can comprise forming an amorphous silicon over the array of storage elements. The semiconductor material can be doped to a particular concentration of doping ions. The semiconductor material can be doped subsequent to all heating cycles associated with forming the array of storage elements. Sensing circuitry can be formed in the semiconductor material. Prior to forming the array of storage elements, a plurality of access transistors can be formed in the base substrate material. The particular concentration of doping ions can be higher than a concentration of doping ions of the base substrate material. Global metal interconnects and pads can be formed over the sensing circuitry.

FIG. 5 is a schematic diagram illustrating sensing circuitry 506 in accordance with a number of embodiments of the present disclosure. The sensing circuitry 506 can be analogous to the sensing circuitry 106 illustrated in FIG. 1. The sensing circuitry 506 can include a sense amplifier 580, which can be analogous to the sense amplifiers 380 and 380 a illustrated in FIG. 3, and a compute component 582, which can be analogous to the compute components 382 and 382 a illustrated in FIG. 3. The compute component 582 can comprise a plurality of compute transistors. FIG. 5 shows a sense amplifier 580 coupled to a pair of complementary digit lines BL-1 and BL-2 (which can be analogous to the pair of complementary digit lines BL-1 and BL-2 and BL-1 and BL-2 illustrated in FIGS. 3 and 4). The compute component 582 is coupled to the sense amplifier 580 via pass transistors 570-1 and 570-2. The gates of the pass transistors 570-1 and 570-2 can be controlled by a logical operation selection logic signal, PASS, which can be output from logical operation selection logic 572. FIG. 5 shows the compute component 582 labeled “A” and the sense amplifier 580 labeled “B” to indicate that the data value stored in the compute component 582 is the “A” data value and the data value stored in the sense amplifier 580 is the “B” data value shown in the logic tables illustrated with respect to FIG. 6.

The selectable logical operation selection logic 572 includes the swap transistors 576, as well as logic to drive the swap transistors 576. The logical operation selection logic 572 includes four logic selection transistors: a logic selection transistor 590 coupled between the gates of the swap transistors 576 and a TF signal control line, a logic selection transistor 592 coupled between the gates of the pass transistors 570-1 and 570-2 and a TT signal control line, a logic selection transistor 594 coupled between the gates of the pass transistors 570-1 and 570-2 and a FT signal control line, and a logic selection transistor 596 coupled between the gates of the swap transistors 576 and a FF signal control line. Gates of the logic selection transistors 590 and 592 are coupled to the true digit line BL-1 through isolation transistor 574-1 (having a gate coupled to an ISO signal control line). Gates of the logic selection transistors 594 and 596 are coupled to the complementary digit line BL-2 through isolation transistor 574-2 (also having a gate coupled to an ISO signal control line).

The plurality of compute transistors of the compute component 582 can include, but are not limited to, the logic selection transistors 590, 592, 594, and 596. That is to say that the logic selection transistors 590, 592, 594, and 596 are a subset of the plurality of compute transistors. As illustrated in FIG. 6, logic selection control signals can be applied to the logic selection transistors 590, 592, 594, and 596 to perform a particular logical operation. Thus, the logic selection transistors 590, 592, 594, and 596 can comprise a semiconductor material (e.g., the second semiconductor material 264 illustrated in FIG. 2), which is formed after the processing steps (e.g., heating cycles cycles) associated with forming storage elements. As a result, when the semiconductor material is doped to a particular concentration of doping ions, the particular concentration can be maintained. The particular concentration can be higher than that of other semiconductor materials of an IMI device. As a result, the logic selection transistors 590, 592, 594, and 596 can be doped to high concentration of doping ions such that the logic selection transistors 590, 592, 594, and 596 have short switching times corresponding to faster operation of an IMI device.

Operation of the logic selection transistors 590 and 596 are based on the state of the TF and FF selection signals and the data values on the respective complementary digit lines at the time the ISO signal is activated/deactivated. The logic selection transistors 590 and 596 also operate in a manner to control the swap transistors 576. For instance, to OPEN (e.g., turn on) the swap transistors 576, either the TF control signal is activated (e.g., high) with data value on the true digit line BL-1 being “1,” or the FF control signal is activated (e.g., high) with the data value on the complement digit line BL-2 being “1.” If either the respective control signal or the data value on the corresponding digit line (e.g., the digit line to which the gate of the particular logic selection transistor is coupled) is not high, then the swap transistors 576 will not be OPENed despite conduction of a particular logic selection transistor 590 and 596.

The PASS* control signal is not necessarily complementary to the PASS control signal. It is possible for the PASS and PASS* control signals to both be activated or both be deactivated at the same time. However, activation of both the PASS and PASS* control signals at the same time shorts the pair of complementary digit lines BL-1 and BL-2 together. Logical operations results for the sensing circuitry illustrated in FIG. 5 are summarized in the logic table illustrated in FIG. 6.

The sense amplifier 580 can, in conjunction with the compute component 582, be operated to perform various logical operations using data from an array as an input. In a number of embodiments, the result of a logical operation can be stored back to the array without transferring the data via a digit line address access (e.g., without firing a column decode signal such that data is transferred to circuitry external from the array and sensing circuitry via local I/O lines). As such, a number of embodiments of the present disclosure can enable performing logical operations and compute functions associated therewith using less power than various previous approaches. Additionally, since a number of embodiments can eliminate the need to transfer data across I/O lines in order to perform compute functions (e.g., between memory and discrete processor), a number of embodiments can enable an increased parallel processing capability as compared to previous approaches.

The sense amplifier 580 can further include equilibration circuitry, which can be configured to equilibrate the pair of complementary digit lines BL-1 and BL-2. In this example, the equilibration circuitry comprises a transistor coupled between the pair of complementary digit lines BL-1 and BL-2. The equilibration circuitry also comprises transistors each having a first source/drain region coupled to an equilibration voltage (e.g., VDD/2), where VDD is a supply voltage associated with the array. A second source/drain region of a transistor can be coupled to the digit line BL-1, and a second source/drain region of a transistor can be coupled to the digit line BL-2. Gates of the transistors can be coupled together, and to an equilibration (EQ) control signal line. As such, activating EQ enables the transistors, which effectively shorts the pair of complementary digit lines BL-1 and BL-2 together and to the equilibration voltage (e.g., VDD/2).

Although FIG. 5 shows sense amplifier 580 comprising the equilibration circuitry, embodiments are not so limited, and the equilibration circuitry may be implemented discretely from the sense amplifier 580, implemented in a different configuration than that shown in FIG. 5, or not implemented at all.

As shown in FIG. 5, the compute component 582 can also comprise a latch 591. The latch 591 can include a pair of cross coupled p-channel transistors (e.g., PMOS transistors) having their respective sources coupled to a supply voltage (e.g., VDD). The latch 591 can include a pair of cross coupled n-channel transistors (e.g., NMOS transistors) having their respective sources selectively coupled to a reference voltage (e.g., ground), such that the latch 591 is continuously enabled. The configuration of the compute component 582 is not limited to that shown in FIG. 5.

FIG. 6 is a logic table illustrating selectable logic operation results implemented by sensing circuitry (e.g., sensing circuitry 506 shown in FIG. 5) in accordance with a number of embodiments of the present disclosure. The four logic selection control signals (e.g., TF, TT, FT, and FF), in conjunction with a particular data value present on the complementary digit lines (e.g., the pair of complementary digit lines BL-1 and BL-2 shown in FIG. 5), can be used to select one of a plurality of logical operations to implement involving the starting data values stored in the sense amplifier 580 and the compute component 582. The four logic selection control signals (e.g., TF, TT, FT, and FF), in conjunction with a particular data value present on the complementary digit lines (e.g., on nodes S and S*), controls the pass transistors 570-1 and 570-2 and swap transistors 576, which in turn affects the data value in the compute component 582 and/or sense amplifier 580 before/after firing. The capability to selectably control the swap transistors 576 facilitates implementing logical operations involving inverse data values (e.g., inverse operands and/or inverse result), among others.

Logic Table 6-1 illustrated in FIG. 6 shows the starting data value stored in the compute component 582 shown in column A at 671, and the starting data value stored in the sense amplifier 580 shown in column B at 673. The other three column headings in Logic Table 6-1 refer to the state of the pass transistors 570-1 and 570-2 and the swap transistors 576, which can respectively be controlled to be OPEN or CLOSED depending on the state of the four logic selection control signals (e.g., TF, TT, FT, and FF), in conjunction with a particular data value present on the pair of complementary digit lines BL-1 and BL-2 when the ISO control signal is asserted. The “NOT OPEN” column 675 corresponds to the pass transistors 570-1 and 570-2 and the swap transistors 576 both being in a non-conducting condition. The “OPEN TRUE” column 677 corresponds to the pass transistors 570-1 and 570-2 being in a conducting condition. The “OPEN INVERT” column 679 corresponds to the swap transistors 576 being in a conducting condition. The configuration corresponding to the pass transistors 570-1 and 570-2 and the swap transistors 576 both being in a conducting condition is not reflected in Logic Table 6-1 since this results in the digit lines being shorted together.

Via selective control of the pass transistors 570-1 and 570-2 and the swap transistors 576, each of the three columns 675, 677, and 679 of the upper portion of Logic Table 6-1 can be combined with each of the three columns 675, 677, and 679 of the lower portion of Logic Table 6-1 to provide nine (e.g., 3×3) different result combinations, corresponding to nine different logical operations, as indicated by the various connecting paths shown at 681. The nine different selectable logical operations that can be implemented by the sensing circuitry 506 are summarized in Logic Table 6-2.

The columns of Logic Table 6-2 show a heading 683 that includes the states of logic selection control signals (e.g., FF, FT, TF, TT). For example, the state of a first logic selection control signal (e.g., FF) is provided in row 684, the state of a second logic selection control signal (e.g., FT) is provided in row 685, the state of a third logic selection control signal (e.g., TF) is provided in row 686, and the state of a fourth logic selection control signal (e.g., TT) is provided in row 687. The particular logical operation corresponding to the results is summarized in row 688.

It will be understood that when an element is referred to as being “on,” “connected to” or “coupled with” another element, it can be directly on, connected, or coupled with the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled with” another element, there are no intervening elements or layers present.

Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that an arrangement calculated to achieve the same results can be substituted for the specific embodiments shown. This disclosure is intended to cover adaptations or variations of one or more embodiments of the present disclosure. It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description. The scope of the one or more embodiments of the present disclosure includes other applications in which the above structures and methods are used. Therefore, the scope of one or more embodiments of the present disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

In the foregoing Detailed Description, some features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the disclosed embodiments of the present disclosure have to use more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. 

What is claimed is:
 1. An apparatus, comprising: a base substrate material; an array of memory cells formed over the base substrate material, wherein the array includes a plurality of access transistors comprising a first semiconductor material; and a compute component formed over and coupled to the array, wherein the compute component includes a plurality of compute transistors comprising a second semiconductor material.
 2. The apparatus of claim 1, wherein the second semiconductor material has a higher concentration of doping ions than the first semiconductor material.
 3. The apparatus of claim 2, wherein the higher concentration of doping ions corresponds to a higher leakage current of the plurality of compute transistors than that of the plurality of access transistors.
 4. The apparatus of claim 2, wherein the higher concentration of doping ions corresponds to a shorter refresh cycle of the plurality of compute transistors than that of the plurality of access transistors.
 5. The apparatus of claim 1, further comprising a plurality of metal interconnects interconnecting the plurality of access transistors, the array, and the compute component.
 6. The apparatus of claim 1, wherein the second semiconductor material has a lower concentration of doping ions than the first semiconductor material.
 7. The apparatus of claim 1, wherein the base substrate material comprises a monocrystalline silicon base substrate material, the first semiconductor material comprises an amorphous silicon first semiconductor material, and the second semiconductor material comprises an amorphous silicon second semiconductor material.
 8. The apparatus of claim 1, further comprising global metal interconnects and pads formed on the compute component.
 9. The apparatus of claim 1, further comprising sensing circuitry, wherein the sensing circuitry comprises: the compute component; and a sense amplifier coupled to the compute component.
 10. The apparatus of claim 9, wherein the sensing circuitry is configured to perform logic operations on data stored in the array.
 11. The apparatus of claim 1, wherein the array comprises a DRAM array.
 12. The apparatus of claim 1, wherein each of the memory cells comprises: a first access transistor; a second access transistor; and a capacitor, wherein the first and second access transistors comprise the first semiconductor material.
 13. The apparatus of claim 12, wherein the array of memory cells further comprises: a plurality of pairs of complementary digit lines; and a plurality of access lines, wherein each of the memory cells are coupled to an associated one of the plurality of pairs of complementary digit lines and an associated one of the plurality of access lines, and wherein the first and second access transistors and the capacitor are coupled in series between the associated one of the plurality of pairs of complementary digit lines with the first and second access transistors sandwiching the capacitor therebetween, and each of the first and second access transistors being at a gate to the associated one of the plurality of access lines.
 14. The apparatus of claim 12, wherein the array comprises: a first memory array tier comprising a first portion of the array; and a second memory array tier comprising a second portion of the array, wherein the second memory array tier is on the first memory array tier.
 15. The apparatus of claim 14, wherein the array further comprises: a third memory array tier comprising a third portion of the memory cells, wherein the third memory array tier is on the second memory array tier; and a fourth memory array tier comprising a fourth portion of the array, wherein the fourth memory array tier is on the third memory array tier.
 16. An apparatus, comprising: a controller; a memory array coupled to the controller, comprising: a plurality of access transistors formed in a monocrystalline silicon base substrate material having a first concentration of doping ions; and an array of storage elements; compute component including a plurality of compute transistors comprising an amorphous silicon semiconductor material having a second concentration of doping ions and coupled to the array; and a plurality of metal interconnects interconnecting, the plurality of access transistors, the array, and the compute component, wherein the compute component is formed over the array, wherein the second concentration is higher than the first concentration, and wherein the controller is configured to cause data to be transmitted, via the plurality of metal interconnects, between the plurality of access transistors, the array, and the compute component.
 17. The apparatus of claim 16, wherein the memory array further comprises a plurality of sense amplifiers formed in the monocrystalline silicon base substrate material, wherein the plurality of metal interconnects interconnect the plurality of access transistors, the array, the compute component, and the plurality of sense amplifiers, and wherein the controller is configured to cause data to be transmitted, via the plurality of metal interconnects, between the plurality of access transistors, the array, the compute component, and the plurality of sense amplifiers.
 18. The apparatus of claim 16, further comprising global metal interconnects and pads formed over and coupled to the compute component, wherein the controller is coupled to the global metal interconnects and pads and configured to cause data to be transmitted to and from the array via the global metal interconnects and pads.
 19. The apparatus of claim 16, further comprising sensing circuitry, wherein the sensing circuitry comprises: the compute component; and a sense amplifier coupled to the compute component, wherein the compute component comprises: logical operation selection logic comprising the plurality of compute transistors, wherein logical operation selection logic controlled to perform a selected logical operation from among a plurality of logical operations based on one or more logic selection control signals applied to the plurality of compute transistors, and wherein the selected logical operation is performed on a data value stored in at least one of the compute component and the sense amplifier.
 20. The apparatus of claim 19, wherein the logical operation selection logic is controlled to perform the selected logical operation based on a data value present on a pair of complementary digit lines.
 21. The apparatus of claim 19, wherein the sensing circuitry is configured to perform the logical operation without transferring data via an input/output (I/O) line.
 22. A method, comprising: forming an array of storage elements over a base substrate material; forming a plurality of compute transistors comprising a semiconductor material over the array; doping the semiconductor material to a particular concentration of doping ions; and forming sensing circuitry in the semiconductor material.
 23. The method of claim 22, wherein forming the plurality of compute transistors comprises forming an amorphous silicon over the array.
 24. The method of claim 22, wherein doping the semiconductor material is subsequent to all heating cycles associated with forming the array.
 25. The method of claim 22, further comprising, prior to forming the array, forming a plurality of access transistors in the base substrate material, wherein the particular concentration of doping ions is higher than a concentration of doping ions of the base substrate material. 